Texas Instruments (TI) has developed packaging technology that enables isolated power modules with up to three times higher power density than discrete solutions, shrinking solution size by as much as 70%, writes Nick Flaherty.

The IsoShield technology integrates a planar transformer and isolated power stage to dramatically reduce the footprint and height of isolated gate drivers for EV powertrain designs.

Expectations of EV performance continue to evolve, requiring engineers to support high battery voltages and faster switching speeds while reducing vehicle weight, improving efficiency and providing galvanic isolation to protect systems from transients and noise in harsh environments with extreme temperatures, vibration and electromagnetic interference (EMI).

Traditional inductor–inductor–capacitor resonant converter and flyback designs require transformers that consume precious board space and height. Discrete transformer-based designs also add unwanted electrical effects that reduce noise immunity and increase design complexity.

The UCC34141-Q1 is an automotive-qualified version of the technology with a footprint of 5.85 mm x 7.5 mm and height of 2.6 mm for an output voltage of 6–20 V – a 70% reduction in size for a 1.5 W DC–DC converter.

“Packaging innovation is revolutionising the power industry, with power modules at the forefront of this transformation,” said Kannan Soundarapandian, vice president and general manager, High Voltage Products at TI. “One of the biggest power problems is power density. The challenge is to fit more power into ever smaller spaces and one of the best ways to do that is integration.

“IsoShield provides an isolation barrier in the middle through an internal air core planar transformer in a System-in-Package,” he said. “This is aimed at any application that needs a high side switch and automotive is an obvious market. The smaller and lighter you can make it, the more advantage you have. Being lighter and smaller also makes it a lot more tolerant to vibration and board-level reliability issues.”

The smaller size allows for more distributed designs to provide redundancy.

“We have been working on improving the isolated bias modules and that means we tried different things internally. What’s unique about IsoShield is how it builds on the packing technology that we were already using,” said David Snook, product line manager at TI. “This becomes an integral part of the packaging flow, and that’s why we have been able to shrink sizes and height even further by 40% compared to the prior generation.”

The device improves thermal performance by as much as 30% compared with previous modules – and in a package that is 54% smaller. These modules only need small, inexpensive EMI filtering to pass CISPR 32 Class B and CISPR 25 Class 5 requirements.

For common-mode transient immunity (CMTI), the module features less than 3 pF of parasitic capacitance across the primary and secondary windings of the integrated transformer, enabling a CMTI of 250 V/ns.